With the popularity of networks and mobile devices, people have a growing demand for wireless communications, and the radio frequency (RF) power amplifier is a key component in wireless communications. The RF power amplifier can amplify signals at specific frequencies, allowing steady RF signals to be received to deliver information, implementing wireless communications. In order to adapt to different environments, the RF amplifier usually requires great energy to amplify the RF signals to the required intensity. However, during the high-power amplification, the RF amplifier will lose linearity of amplification, resulting in signal distortion.
In addition, since the RF amplifier is usually disposed at the last stage of the signal transmitter, the linearity of the RF amplifier will affect the quality of wireless communications directly. An important factor that causes the linearity loss of the RF amplifier is the third-order intercept and intermodulation (IM3). The third-order intercept and intermodulation is generated at the output terminal of the RF amplifier after two or more input signals of similar frequencies being amplified by the RF amplifier nonlinearly. Since the frequency of the third order intercept and intermodulation is the closest to the frequency of the input signals, it is very difficult to filter out the third-order intercept and intermodulation by the filter.